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const COLS = 80;
const ROWS = 25;
/// Clear screen (all black).
fn clear_screen(video: []u16) void {
for (video) |*ch| {
ch.* = 0;
}
}
/// Draw the color palette.
fn draw_palette(video: []u16) void {
// Each framebuffer entry in text mode is 16bit wide.
// [15] blink
// [14:12] bg color (3 bit)
// [11: 8] fg color (4 bit)
// [ 7: 0] ascii character
//
// https://en.wikipedia.org/wiki/VGA_text_mode
// Print each bg / fg combination once.
for (video, 0..0x80) |*ch, i| {
ch.* = @as(u16, @truncate(i)) << 8 | 'a';
}
}
// kmain should be "callconv(.naked)", once issue is fixed.
// https://github.com/ziglang/zig/issues/18183
export fn kmain() noreturn {
// Take a slice to VGA video memory (mode 3h text mode 80x25).
const video: []u16 = @as([*]u16, @ptrFromInt(0xB8000))[0 .. COLS * ROWS];
clear_screen(video);
draw_palette(video);
while (true) {
asm volatile ("hlt");
}
}
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